Facultad Regional Córdoba
Permanent URI for this communityhttp://48.217.138.120/handle/20.500.12272/94
Browse
5 results
Search Results
Item Hydrogenation of tetralin in presence of nitrogen using a noble-bimetallic couple over a Ti-modified SBA-15.(Univesidsad Tecnológica Nacional., 2016) Vallés , Verónica Alejandra; Ledesma , Brenda Cecilia; Pecchi, Gina; Anunziata , Oscar Alfredo; Beltramone , Andrea Raquel; Anunziata , Oscar Alfredo; Ledesma , Brenda CeciliaMonometallic Pt- and bimetallic Pt-Ir-modified Ti-SBA-15 were used in the hydrogenation of tetralin to decalin in the presence of 150 ppm of N as quinoline and indole at 250 ◦C and 15 atm of pressure of hydrogen, using a Parr reactor. The catalyst was synthesized using sol-gel method and Ti was added during the synthesis using Tetraethyl Orthotitanate. Pt/Ir was added by wetness impregnation. The catalysts prepared were extensively characterized by X-ray diffraction (XRD), N2 adsorption isotherms, UV–vis DRS, Raman spectroscopy, XPS, TEM-EDS and TPR. UV–vis-DRS and Raman spectroscopy confirmed that Ti was incorporated in tetrahedral coordination in the framework of the SBA-15. The analysis showed that the mesoporous structure was maintained after metal incorporation and Ti incorporation helps to reduce significantly the size of the metals clusters and improves its dispersion considerably. Pt-Ir/Ti-SBA 15 was the most active catalyst. The experimental data were quantitatively represented by a modified Langmuir-Hinshelwood type rate equation. The preliminary results show these materials as a promising catalyst for HDT reactions.Item Hydrogenation of tetralin in presence of nitrogen using a noble-bimetallic couple over a Ti-modified SBA-15.(Univesidsad Tecnológica Nacional., 2017) Vallés , Verónica Alejandra; Ledesma , Brenda Cecilia; Rivoira , Lorena Paola; Cussa , jorgelina; Anunziata , Oscar Alfredo; Beltramone, Andrea Raquel; Cussa , jorgelina; Rivoira , Lorena Paola; Ledesma , Brenda CeciliaThe increased attention paid to catalytic hydrogenation in the oil refining industry is due in part to legislation regarding the maximum contents of sulfur, aromatic compounds, and alkenes in traffic fuels. Aromatics in diesel increase the particle emissions in exhaust gases and they have the further effect of lowering the fuel quality. Many factors such as the catalysts, process parameters, feedstock source and quality, reactivities of sulfur compounds, inhibition effects of H2S, nitrogen compounds and aromatics present in the feed, etc. can have significant influences on the degree of hydrogenation of diesel feeds1,2. Recently, studies have been reviewed and the investigations have also been extended to noble metals3 . In our previous investigations with bimetallic catalysts4 , we had very good results preparing the catalysts by co impregnation of the relevant metals on the SBA-15 mesoporous matrix. These studies showed high activity, selectivity and stability as well also greater resistance to poisons compared to monometallic catalysts. In this contribution titanium is incorporated in tetrahedral position replacing silicon in the mesoporous framework. We expect that Ti incorporation improve the dispersion of the bimetallic clusters. In the present work three compounds tetralin, indole and quinoline were used as models for the compounds in diesel. The model compounds were hydrogenated both separately and as mixtures in order to study the inhibition effect.Item Iridium-supported SBA-15 modified with Ga and Al as a highly active catalyst in the hydrodenitrogenation of quinoline(2020) Ledesma, Brenda Cecilia; Martínez, María Laura; Beltramone, Andrea RaquelIr-supported SBA-15 was studied in the hydrodenitrogenation (HDN) of quinoline as a model nitrogen com- pound. The activity was improved when Si-SBA-15 support was modified with Ga and Al. Characterization of the catalysts was performed by XRD, N2 adsorption, XPS, H2 chemisorption, TEM, TPR, NMR and Py-FTIR. Dispersion and nature of the iridium species are dependent parameters on the support characteristics. Better activity for the elimination of the nitrogen atom was observed with Ir-Ga-SBA-15 as compared to Ir-Al-SBA-15 at 250 and 300 °C. However, the TON value for Ir-Al-SBA-15 was higher than Ir-Ga-SBA-15 at 300 °C, indicating the influence of the stronger Bronsted acidity in the elimination of the nitrogen atom at higher temperature. The enhanced activity was attributed to the particularly good dispersion of the iridium catalytic centers and to the synergic effect of Bronsted and Lewis acid sites, derived from Ga or Al incorporation. Ga-SBA-15 with 1 wt.% of iridium loading was the most active catalyst for HDN of quinoline. 95% of nitrogen elimination was attained at short time in mild conditions. The reusability of the catalyst presents it as potential catalyst for HDN process.Item Hydrogenation of tetralin over Ir-containing mesoporous catalysts(2012) Vallés, Verónica; Balangero, Gerardo Simón; Martínez, María Laura; Gómez Costa, Marcos Bruno; Anunziata, Oscar Alfredo; Beltramone, Andrea RaquelThe yield in fluid catalytic cracking (FCC) depends on the extent of aromatic hydrogenation in the gas oil hydrotreater. To optimize the gas oil hydrotreater, it is crucial to understand the aromatic hydrogenation reaction chemistry occurring in the gas oil hydrotreater. Gas oils, which consist of hydrocarbons in the boiling point range of 290−570 °C, contain several aromatic compounds (including three rings, two rings, and one ring). Light cycle oil (LCO), which contains large concentrations of aromatics, has a poor cetane value and, hence, by itself, is a very poor-quality diesel. Because the current regulations [on cetane and polynuclear aromatic (PNA) hydrocarbons] are not stringent, LCO is currently blended with diesel. However, it is anticipated (based on existing regulations in Europe and California) that diesel quality in the near future will be more stringently regulated in terms of cetane and aromatics. To find alternative processes, it is necessary to develop new and more active catalysts to replace the current ones. Optimal design and operation of such hydrogenation processes can be achieved through the use of reliable simulation tools; however, such tools require detailed knowledge of kinetic pathways and rates.1−3 Kinetic experiments on hydrogenation are typically performed in the gas phase under atmospheric pressure on group VIII metal catalysts. Previously, Beltramone et al.4,5 reported a detailed study and a quantitative network analysis of polynuclear aromatics aromatization at industrial conditions, and Korre and Klein6 reported an exhaustive study in a batch reactor at high pressure. Otherwise, the sulfur and nitrogen compounds found in synthetic feedstocks and heavy petroleum fractions can strongly inhibit hydroprocessing reactions through competitive adsorp- tion. The presence of these species even at low concentrations can limit the observed catalytic activity and necessitate the use Article Current processes for dearomatization use catalysts combin- ing the acidity of a support and the hydrogenation and hydrogenolysis/ring-opening activity of an incorporated metal. Hydrogenation/hydrocracking is most often practiced on cyclic molecules over primarily acidic zeolite, alumina, or silica- alumina-supported noble and other group VIII metal catalysts. Different processes have used catalysts such as NiMo, CoMo, NiW, Pt, and Pd on various supports.7−17 The dominance of the acid function can lead to cracking, and thus, a primary focus is the optimization of the acid function. In fact, it was shown recently that significant enhancements in hydrogenation can be made by focusing on the metal function. The metal function is usually provided by Pt and/or Pd, but it has been shown that Ir, Ru, and Rh also have exceptional activities and selectivities for the target reaction of hydrogenation and, depending on the reaction conditions, selective ring-opening.18−20 Some alumina- supported transition-metal catalysts have much higher hydro- denitrogenation (HDN) and hydrodesulfurization (HDS) activities than the conventional NiMo system.21−25 For example, Rh, Ir, Ru, and Pt supported on silica or alumina are known to effectively catalyze nitrogen removal from methylamine, quinoline, or pyridine also in the reduced state.26 Noble-metal sulfides, either unsupported as bulk compounds27 or supported on active carbon,28 have been studied extensively in hydrorefining. It has been shown that transition-metal sulfides of the second and third rows such as those containing Ru, Rh, Os, and Ir are especially active during HDS reactions.27 Similarly, sulfides of Ir, Os, and Re were found to be most active in the HDN of quinoline,28 and sulfides of Ir and Pt were found to be most active in the HDN of pyridine.29 However, catalytic properties of metal deposited on alumina or other supports have been studied less frequently, and moreover, the primary attention to date has been devoted only to Ru.30 It was shown by Cinibulk and Vit́31 that the HDN of higher pressures and temperatures to obtain desired conversions. Therefore, the need for more active catalysts is crucial in this process. The development of highly active and selective hydrotreating catalysts is one of the most pressing problems facing the petroleum induItem Magnetic fe304@si02-pt and fe304@si02-pt@si02 structures for hdn of índole.(2020) Dinamarca, Robinson; Valles, Verónica A.; Ledesma, Brenda; Campos, Cristian; Pecchi, Gina; Beltramone, Andrea R.Se informa el efecto de una segunda cubierta porosa de SiO2 en la actividad y selectividad del catalizador Fe3O4@SiO2-Pt en la hidrodenitrogenación de indol. La doble estructura de Fe3O4@SiO2-Pt se preparó recubriendo nanopartículas de Fe3O4 con TEOS y una impregnación adicional de 1,0% en peso de Pt en la estructura de Fe3O4@SiO2 funcionalizada con (3-aminopropilo)trietoxisilano. La segunda cubierta porosa de SiO2, obtenida utilizando la plantilla CTAB, con una distribución de tamaño de poro estrecha y bien definida, cubrió el catalizador Fe3O4@SiO2-Pt. La caracterización completa por TEM, ICP-OES, XRD, isoterma de adsorción de N2 a 77 K y VSM de los catalizadores indica estructuras homogéneas core@shell con un nano tamaño controlado de Pt metálico. Se demostró un efecto significativo de la doble capa de SiO2 en el rendimiento catalítico tanto por una mayor actividad para eliminar el átomo de nitrógeno de la molécula de indol, presente en el combustible líquido modelo, como por la mejora de la estabilidad catalítica, lo cual se observa en la obtención de cuatro ciclos de reacción consecutivos con solo una ligera disminución en la conversión.